8

Set 3: Ratios Rates Proportions (Advanced)

Explanation

Answer: B

PROBLEM

A mixture is made of two substances in the ratio 3:4. If the total mixture is 42 liters, how many liters is the first substance?

A mixture is made of two substances in the ratio 3:4. If the total mixture is 42 liters, how many liters is the first substance?

A.

20

B.

18

✓ Correct
C.

36

D.

16

Detailed Explanation

Choice B is the best answer. First substance = 3/(3+4) times 42 = 3/7 times 42 = 18 liters

Why others are wrong:
A: 20 is incorrect because it does not satisfy the equation.
C: 36 is incorrect because it does not satisfy the equation.
D: 16 is incorrect because it does not satisfy the equation.